1-丁基-3-甲基咪唑六氟磷酸盐中PCl_5催化的两相贝克曼重排反应

TWO PHASE BECKMANN REARRANGEMENT WITH [PF_6] IONIC LIQUIDS USING PCl_5 AS CATALYST

在 1 丁基 3 甲基咪唑六氟磷酸盐 ([bmim][PF6])离子液体与甲苯组成的两相体系中 ,以PCl5为催化剂 ,实现了由环己酮肟制备己内酰胺的高效、高选择性液相贝克曼重排反应。该两相体系有利于实现反应控制和体系取热。分别考察了环己酮肟用量、PCl5用量、离子液体体积、反应温度和反应时间对环己酮肟转化率、己内酰胺选择性和PCl5的催化转化数的影响。优化的重排反应条件是 :2 .0mL [bmim][PF6]/ 5 .0 0mL甲苯 ,0 .4 0 5gPCl5,10 .0mmol环己酮肟 ,80℃ ,反应时间 10～ 30mim。在此条件下 ,环己酮肟转化率达 99.72 % ,己内酰胺选择性达 98.90 % ,PCl5的催化转化数达 5 .14。 99.5 %以上的己内酰胺在离子液体相。

Beckmann rearrangement of cyclohexanone oxime was effectively realized to prepare ε-caprolactam when using phosphorous pentachloride (PCl 5 ) as catalyst in twophase systems composed of 1-n-butyl-3-methylimidazolium hexafluorophosphate(\\[PF 6 \]) ionic liquids and toluene. The system of two phases facilitated to control the rate and remove the reaction heat. The effects of the amount of cyclohexanone oxime, the amount of PCl 5 , the volume of the ionic liquids, reaction temperature and reaction time on the conversion of cyclohexanone oxime, the selectivity of caprolactam and the turn over number (TON) of PCl 5 were studied. The optimized conditions were 2.0ml \\[PF 6 \]/ 5.00ml toluene/0.405g PCl 5 /10.0mmol cyclohexanone oxime at 80℃ reacting 10-30min. At above conditions, the conversion of cyclohexanone oxime, the selectivity of ε-caprolactam and the TON of PCl 5 could reach 99.72%, 98.90% and 5.14 respectively. Almost all the ε-caprolactam (>99.5%) existed in the ionic liquids phase.